1. Field of the Invention:
This invention relates to a novel phosphoric acid ester and a novel detergent composition, and, more particularly, to a phosphoric acid ester represented by the following formula (I): ##STR2## wherein R.sub.1 represents a linear or branched alkyl or alkenyl group having a C.sub.1-36 carbon atom content, with or without the hydrogen atom(s) being substituted with fluorine atom(s), or a phenyl group with substituted linear or branched alkyl group(s) having a C.sub.1-15 carbon atom content, R.sub.2 represents an alkylene group having a C.sub.2-3 carbon atom content, R.sub.3 and R.sub.4 independently denote a hydrogen atom or an alkyl group having a C.sub.1-3 carbon atom content, R.sub.5 and R.sub.6 independently denote a hydrogen atom, or an alkyl, alkenyl, or phenyl group with or without the hydrogen atom(s) being substituted with group(s) containing hetero atom(s), excepting for a mercapto group, m is an integer of 0-30, n is an integer of 0-5, M is a hydrogen atom, an alkali metal, an alkali earth metal, an ammonium group, an alkyl amine group, or an alkanol amine group. The invention also relates to a a phosphoric acid ester represented by the following formula (IX): ##STR3## wherein R.sub.7 and R.sub.8 independently denote a hydrogen atom, or an alkyl or alkenyl group, and 1 is an integer of 0-3, and R.sub.1, R.sub.2, R.sub.3, R.sub.4, m, and M have the same meanings as defined above. The invention also is directed to processes for preparing the above phosphoric acid esters, as well as detergent compositions comprising the same.